Abstract
Purpose :
Significant neuronal changes in the retina can happen much earlier than clinically-apparent vascular changes in diabetic retinopathy (DR), (Pescosolido et al., 2015). Pattern ERG (PERG) changes reveal early ganglion cell (RGC) dysfunction and RGC loss in DR (Caputo et al., 1999, Jackson & Barber, 2010; Ng et al., 2016). Delayed flash ERG oscillatory potential (OP) implicit times (Tezkov & Arden, 1999) are also strong indications of early disease manifestation. Recently described peripheral PERG (pPERG) responses (Patangay et al., 2018) contain novel high frequency components, similar to flash ERG OPs. Our hypothesis is that these pPERG high frequency components may be of clinical relevance in assessing inner-retina dysfunction of the peripheral retina. Here, an initial evaluation of pPER high frequency component amplitudes and implicit times in normally-sighted subjects and in DR patients are described.
Methods :
Fifteen normally-sighted subjects and two non-proliferative diabetic retinopathy patients (NPDR, mild and moderate stages) were recruited. A three-dimensional pattern stimulus source was used to present a reversing checkerboard pattern (8o checks, 4.6 RPS, mean luminance of ON-checks 1670 ph cd m-2) to the peripheral retina. The stimulus extended from 27o – 60o of visual angle in all directions. For each subject, responses to approximately 300 pattern reversals were recorded (passband 1-300 Hz) and averaged for analysis. A zero-phase-shift 8th order Butterworth filter with passband 50-300 Hz was used to isolate the high-frequency response components. The three high-frequency oscillations, named F1, F2 and F3, were evaluated for amplitudes and implicit times, yielding six feature values for each subject.
Results :
In both NPDR patients, the F1, F2 and F3 implicit times were delayed, and outside of the 95% confidence interval for the reference range. Both patients also had reduced amplitudes for all three components, outside of the 95% confidence interval for the reference range.
Conclusions :
High frequency components observed in the pPERG waveforms may be of clinical relevance in assessing inner-retina dysfunction of the peripheral visual field. Changes in pPERG high frequency components in DR may also suggest a similar cellular origin to that of flash OP’s.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.